What is glaucoma?


Glaucoma is frequently called the “sneak thief of sight,” because there are often no symptoms before severe vision loss occurs. This is the leading cause of blindness in the United Stated. An estimated 1 out of 50 adults is affected with this disease. Loss of sight from glaucoma is preventable with early detection and treatment by your optometrist or ophthalmologist. Glaucoma is a series of diseases of the optic nerve. The optic nerve is the messenger between the the eyes and the brain, when it becomes damaged, vision is impaired.

What causes glaucoma?

Glaucoma is caused by pressure in the eye caused by a build up of a fluid, called the aqueous humor. The aqueous humor circulates through the eye, nourishing the tissues, and then exits the eye through a drainage system called the angle. When this drainage system becomes obstructed, fluid builds up, causing the pressure inside the eye to rise. In some cases, the eye simply produces more aqueous humor than it can drain, which also results in a rise of pressure. This elevated pressure cannot be felt, there are no symptoms or side-effects until damage has already been done to the optic nerve.

What are the different types of glaucoma?

The two main types of Glaucoma are

  • Chronic open-angle glaucoma is the most common type of glaucoma. The drainage angle is open, but working less efficiently, usually due to age. As a result, pressure builds up slowly, causing a gradual loss of side vision. It progresses so slowly it usually goes undetected.
  • Angle-closure glaucoma occurs when the drainage angle of the eye is totally blocked, preventing any fluid to drain. This causes the pressure inside the eye to rise suddenly. This instant rise in pressure can cause halos to appear around lights, blurred vision, headaches and severe eye pain. Call your ophthalmologist or optometrist immediately, if your are experiencing any of these symptoms. Your vision may be in eminent danger. In order to view the content, you must install the Adobe Flash Player. Please click here to get started.

There are several subsets of Chronic Open-Angle and Angle-Closure glaucoma such as

  • Secondary Glaucoma is caused by inflammation of the eye, severe cases of diabetes, the use of steroids or an eye injury. The increase of eye pressure results in optic nerve damage and vision loss.
  • Chronic angle-closure glaucoma is a more gradual and painless closing of the angle. Chronic angle-closure glaucoma occurs more frequently in people of African and Asian ancestry.
  • Normal Tension Glaucoma results in damage of the optic nerve and vision loss without high eye pressures.
  • Congenital Glaucoma is a rare condition in infants that have underdeveloped eyes. It can be easily managed with surgery and/or medication although lost vision will not be restored. 

How is glaucoma detected?

Glaucoma is most often found during a dilated eye examination, which is utterly painless. During an examination, your eye doctor will measure the intraocular pressure of your eye, inspect the drainage angle, evaluate any damage to the optic nerve and test the vision of each eye.It may not be necessary for you to have all of these tests, although it is recommended that you repeat them on a regular basis to determine if optic nerve damage is increasing over time.

Treatment Options

Glaucoma is usually treated in office with prescription eye drops and by laser procedures known as Argon Laser Trabeculectomy (ALT) or Selective Laser Trabeculectomy (SLT).

Who is at risk for glaucoma?

Anyone can get glaucoma, however some people are at a higher risk. They include:

  • African-Americans over age 40
  • Anyone over 60
  • People with a family history of glaucoma
  • People with a history of severe anemia or shock
  • People with past injuries to the eyes
  • People with myopia

Remember, prevention is painless, but sight loss is devastating.


iStent works like the stents used to prevent heart attacks and strokes. When blood vessels get clogged, a stent creates access to the vessel flow. While a highly innovative technology, how iStent works is elegantly simple:

  • If you have glaucoma, over time the eye’s natural drainage system becomes clogged
  • iStent creates a permanent opening through the blockage to improve the eye’s natural outflow
  • Restoring this mechanism lowers and controls pressure within the eye
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iStent: managing glaucoma while treating your cataracts

iStent is implanted during your cataract surgery procedure. Once implanted, iStent will begin working to safely and effectively manage pressure. What’s more, patients who receive iStent may experience a reduction in glaucoma medications; but this will be at the discretion of your physician.

Learn More About iStent From This Educational Video:


The iStent® Trabecular Micro-Bypass Stent (Models GTS100R and GTS100L) is indicated for use in conjunction with cataract surgery for the reduction of intraocular pressure (IOP) in adult patients with mild-to-moderate open-angle glaucoma currently treated with ocular hypotensive medication.


The iStent® is contraindicated in eyes with primary or secondary angle closure glaucoma, including neovascular glaucoma, as well as in patients with retrobulbar tumor, thyroid eye disease, Sturge-Weber Syndrome or any other type of condition that may cause elevated episcleral venous pressure.


Gonioscopy should be performed prior to surgery to exclude PAS, rubeosis, and other angle abnormalities or conditions that would prohibit adequate visualization of the angle that could lead to improper placement of the stent and pose a hazard. The iStent® is MR-Conditional meaning that the device is safe for use in a specified MR environment under specified conditions, please see label for details.